There is a surprisingly long history behind the invention of the electric powered bicycle. People have attempted to motorize personal transport throughout the ages and the bicycle seemed like a perfect platform even back then. This assist model has varied in power and capacity but always included pedaling as an integral part of the propulsion process. It is this integration that has clearly separated electric bicycles from mopeds and motorcycles. As technology improved, the electric motors gained important sensors and controls that allowed the drive system to "Feel" the need for powered support, thus providing the added boost to the rider. The general idea of this technology was to add power only when needed, allowing the bike's power source to last longer and go further on a single charge.
We have just completed our prototypes. Our three subsystems that we have worked on are: motor controller, cadence sensor, and the display. We have been succesfully able to get each of those sub systems to work.
The next steps are to adapt the sub systems to work with the tricycle. We plan to research over the next couple of weeks to begin implementing these into the tricycle.
Final Design
The final product consists of five major subsystems: motor, speed sensor, cadence sensor, torque sensor, and display. The motor can convert electrical energy into mechanical energy. The motor gets powered from the battery and is placed on the front wheel. This will provide power assist to the user when they are pedaling. The motor controller can adjust the speed of the tricycle depending on the user's need. When the full assist mode is activated, the user can then ride without pedaling at all. The controller adjusts the width of the pulses delivered to the motor, which can change the speed. The sensors consist of speed sensor, cadence sensor, and torque sensor. The speed sensor is used to detect the revolutions of the wheel, this information will then be used to calculate the speed at which the tricycle is traveling. The cadence sensor will calculate the revolutions the rider pedals. For this sensor there is a circular device with eight magnet patches on it that are attached to the crank and a sensor reader is placed on the crankarms to measure the riders current cadence. When the wheel revolves one round, the sensor will interact with magnets and send the signal to the Arduino. Arduino receives the signal and can give speed of pedal revolution by calculating that data. The torque sensor is used to calculate how much force the rider is applying to the cranks. This information can be used to inform the rider to use the assistance if needed. The display subsystem is used to display important information such as speed of tricycle, torque data, and battery level on LCD screen to the user. The user can adjust their speed and power assist according to this information.
Click here to download the final video demonstration
